The goal of the project is to improve the selectivity and sensitivity of analytical methodology for anabolic steroids. Our approach has been to use our earlier successes in the chemical oxidation of corticosteroids to enhance or manifest the latent electrophilic character of these analytes to allow them to be selectively detected in extracts of complex tissues. Fluoxymesterone is an anabolic steroid that lends itself to analysis by this specialized analytical procedure. Results have been obtained showing that fluoxymesterone and its metabolites can be detected in urine extracts after they have been chemically oxidized to highly conjugated ketonic structures that are sensitive to detection by electron capture negative ionization mass spectrometry. We have demonstrated that this oxidative methodology permits levels of fluoxymesterone to be detected in urine extracts by ECNI, but that were not detectable by the classical approach of preparing the trimethylsilyl derivative with analysis by electron ionization.